Tooth decay and dental disease can be caused by bacterial action resulting from the formation of plaque about the teeth and/or the entrapment of food particles in interstices between the teeth. Removal of plaque and entrapped food particles reduces the incidence of caries, gingivitis, and mouth odors as well as generally improving oral hygiene. Conventional brushing has been found to be inadequate for removing all entrapped food particles and plaque. To supplement brushing, dental flosses and tapes have been recommended. Dental flosses may include distinct regions, for example, a thickened "brush" portion, a thin "floss" portion, and/or a threader. The brush portion, when drawn between tooth surfaces, provides good cleaning action which removes materials left by a standard thin floss used alone. The threader portion allows the floss to be inserted in a tight space or into an artificial dental appliance.
Dental flosses, both in brush and thin floss form, have been developed that are coated with wax in order to improve durability, feel, and frictional qualities. Waxed dental flosses containing active agents are also known in the art, and in addition to providing for the mechanical removal of food deposits from the internal spaces between teeth, also provide for the release of active agents that will act within the oral environment. Such active agents may prevent tooth decay, or have anti-tartar, antibiotic, antimicrobial, anti-inflammatory, antioxidant, or antiseptic actions.
Active agents added to wax have been found to be problematic due to inefficient release from the insoluble wax. Thus, soluble waxes such as polyethylene glycol-derivative waxes have been use. However, soluble waxes also present problems resulting from harsher sliding and decreased comfort to the user.
The use of emulsified wax has been found to improve waxed floss by allowing an improved efficiency of release of an associated chemotherapeutic product while preserving the comfortable effect obtained with insoluble wax. EP 0637 446 A1 describes a dental floss coated with emulsified wax impregnated with chemotherapeutic agents useful in oral hygiene.
A number of methods for coating wax onto dental floss are known to the art. For example, U.S. Pat. No. 3,838,702 describes a method of guiding a fiber through a liquid bath of the coating material in which the coating material is dissolved in a solvent, and then passing the coated fiber through a heated die or extruder to remove excess coating material and/or to cure the coating with evaporation of the solvent. PCT patent publication WO 92/10978 describes a method of coating a dental filament with wax by using a lick roller. The lick roller is immersed in a wax solution and coats the filament with a layer of wax upon contact with the filament.
Methods of incorporating additives in dental floss are known. For example, methods for impregnating dental floss with a flavoring agent are known in the art, and include direct application with flavor oil-solvent solutions and direct contact with flavor oil in a melted wax solution. Other common additives include mouth conditioning agents such as silicones, cleaners, and abrasives, and desensitizing agents such as strontium chloride. See, for example, PCT patent application publication WO 91/14412.
Existing methods for applying both a chemotherapeutic agent and flavor require a two-step process in which a chemotherapeutic agent, either suspended in an oil phase or dissolved in an aqueous phase, is first applied to the dental floss, followed by application of a flavoring agent dissolved in oil. FIGS. 1A and 1B illustrate typical two-step methods for applying a chemotherapeutic agent and flavor-coating to a dental floss.
There is a need for a more efficient method of applying a chemotherapeutic agent and flavor to dental floss.